The above-indicated sort of printed-board supporting apparatus is well known in the art, and is disclosed by, e.g., the below-identified Patent Document 1 or Patent Document 2. Patent Document 1 discloses a printed-board supporting apparatus employing a plurality of support pins each of which has a reference mark provided on a support surface thereof to support a printed board; a pin supporting table that supports the support pins attached thereto; and an image taking device that takes an image of the reference mark of the each support pin. Based on image data representing the taken image, a position or positions of the each support pin in a horizontal direction or directions is or are calculated, and a positional error or errors of the each support pin is or are calculated. If the positional error or errors goes or go beyond a permission range or ranges, the positioning of the each support pin is judged as being inappropriate, and then is corrected. The printed-board supporting apparatus employing the support pins is mainly used in the case where it is needed to support locally a printed board without interfering with one or more electronic circuit components already mounted on the reverse surface of the board and/or irregularities present on the reverse surface. Therefore, if the positioning of each support pin is inappropriate, the electronic circuit component(s), the printed board, and/or the support pin(s) may be damaged or even broken. Thus, it is needed to position accurately each support pin on the pin supporting table.
In addition, Patent Document 2 discloses a printed-board supporting apparatus employing a plurality of support pins; a pin supporting table that supports the support pins attached thereto to support a printed board; an image taking device that takes an image of the printed board supported by the support pins; and a monitor that displays the taken image of the printed board so that an operator can manually adjust a height of the printed board while observing the image displayed on the monitor. For example, in the case where the current sort of printed boards are changed to a new sort of printed boards each having a different thickness, respective heights of respective support surfaces of the support pins are adjusted according to a height of the reverse surface of the new sort of printed board that is to be supported by the support pins.    Patent Document 1: Japanese Patent Application Publication No. 11-195899    Patent Document 2: Japanese Patent Application Publication No. 2002-185189